The invention relates to equipment and methods for monitoring the condition of machinery by sensing the amplitude (level) and frequency (rate) of machine vibrations and processing the collected vibration data.
Vibration is produced by moving parts of machinery due to causes like unbalance, misalignment of shafts and worn out bearings. Every machine has reasonable levels of vibration that are characteristic of its operation. Excessive levels of vibration indicate machine problems which may lead to unsatisfactory operation and eventual breakdown.
Machine malfunction can sometimes be detected by a change in the audible noise pattern of that machine. Many good mechanics can listen to the operating noise of a machine and thereby pinpoint the source of the problem. In today's plants where machines are complex and/or large in number, engineers rely on more advanced methods of identifying abnormal levels and patterns of vibration (which is heard as noise) in order to determine the condition of a machine. It is now common to measure the level and rate of the vibrations of machines and use this data to determine which machines require servicing. This more reliable monitoring technique is called predictive maintenance.
To properly employ predictive maintenance, vibration data is taken and recorded on a scheduled basis during normal use of the machinery. There are a number of systems available for this purpose. Most are highly complex electronic systems that involve numerous operating steps of an exacting nature and therefore require well trained operators. Such existing equipment usually has a variety of dials and/or keys that must be operated in a certain order. Often the operator must take notes such as the identification of the machine, settings of switches and dials, or of the data collection station on the machine. Even when used by skilled operators, such systems are prone to human error which can result in unnecessary maintenance, or worse yet, the failure to predict major breakdowns. As explained more fully in the detail description, most existing portable vibration data collectors direct the operators to successive machines on a preprogrammed "paper route", with the next machine location displayed on the portable unit. This discourages the operator from choosing an optimum route. Also, some prior collection systems discussed herein permit the operator to enter setup data for each machine station, introducing the possibility of human error, compared to a device that retrieves preloaded data collection setup parameters from memory.